﻿// Copyright © 2010-2017 The CefSharp Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.

using System;
using CefSharp.Enums;
using CefSharp.Structs;

namespace CefSharp.OffScreen
{
	/// <summary>
	/// Implement this interface to handle Offscreen Rendering (OSR).
	/// NOTE: Currently only OnPaint is implemented, at some point expand the API to include all
	/// of CefRenderHandler methods http://magpcss.org/ceforum/apidocs3/projects/(default)/CefRenderHandler.html
	/// </summary>
	public interface IRenderHandler : IDisposable
	{
		/// <summary>
		/// Called to allow the client to return a ScreenInfo object with appropriate values.
		/// If null is returned then the rectangle from GetViewRect will be used.
		/// If the rectangle is still empty or invalid popups may not be drawn correctly. 
		/// </summary>
		/// <returns>Return null if no screenInfo structure is provided.</returns>	
		ScreenInfo? GetScreenInfo();

		/// <summary>
		/// Called to retrieve the view rectangle which is relative to screen coordinates. 
		/// </summary>
		/// <returns>Return a ViewRect strict containing the rectangle or null. If the rectangle is
		/// still empty or invalid popups may not be drawn correctly. </returns>
		ViewRect? GetViewRect();

		/// <summary>
		/// Called to retrieve the translation from view coordinates to actual screen coordinates. 
		/// </summary>
		/// <param name="viewX">x</param>
		/// <param name="viewY">y</param>
		/// <param name="screenX">screen x</param>
		/// <param name="screenY">screen y</param>
		/// <returns>Return true if the screen coordinates were provided.</returns>
		bool GetScreenPoint(int viewX, int viewY, out int screenX, out int screenY);

		/// <summary>
		/// Called when an element should be painted. Pixel values passed to this method are scaled relative to view coordinates based on the
		/// value of <see cref="ScreenInfo.ScaleFactor"/> returned from <see cref="GetScreenInfo"/>.
		/// Called on the CEF UI Thread
		/// </summary>
		/// <param name="type">indicates whether the element is the view or the popup widget.</param>
		/// <param name="dirtyRect">contains the set of rectangles in pixel coordinates that need to be repainted</param>
		/// <param name="buffer">The bitmap will be will be  width * height *4 bytes in size and represents a BGRA image with an upper-left origin</param>
		/// <param name="width">width</param>
		/// <param name="height">height</param>
		void OnPaint(PaintElementType type, Rect dirtyRect, IntPtr buffer, int width, int height);

		/// <summary>
		/// Called when the browser's cursor has changed. . 
		/// </summary>
		/// <param name="cursor">If type is Custom then customCursorInfo will be populated with the custom cursor information</param>
		/// <param name="type">cursor type</param>
		/// <param name="customCursorInfo">custom cursor Information</param>
		void OnCursorChange(IntPtr cursor, CursorType type, CursorInfo customCursorInfo);

		/// <summary>
		/// Called when the user starts dragging content in the web view. Contextual information about the dragged content is
		/// supplied by dragData. (|x|, |y|) is the drag start location in screen coordinates. OS APIs that run a system message
		/// loop may be used within the StartDragging call. Return false to abort the drag operation. Don't call any of
		/// CefBrowserHost::DragSource*Ended* methods after returning false. Return true to handle the drag operation.
		/// Call IBrowserHost::DragSourceEndedAt and DragSourceSystemDragEnded either synchronously or asynchronously to inform
		/// the web view that the drag operation has ended. 
		/// </summary>
		/// <param name="dragData">drag data</param>
		/// <param name="mask">operation mask</param>
		/// <param name="x">x coordinate</param>
		/// <param name="y">y coordinate</param>
		/// <returns>Return false to abort the drag operation.</returns>
		bool StartDragging(IDragData dragData, DragOperationsMask mask, int x, int y);

		/// <summary>
		/// Called when the web view wants to update the mouse cursor during a drag & drop operation.
		/// </summary>
		/// <param name="operation">describes the allowed operation (none, move, copy, link). </param>
		void UpdateDragCursor(DragOperationsMask operation);

		/// <summary>
		/// Called when the browser wants to show or hide the popup widget.  
		/// </summary>
		/// <param name="show">The popup should be shown if show is true and hidden if show is false.</param>
		void OnPopupShow(bool show);

		/// <summary>
		/// Called when the browser wants to move or resize the popup widget. 
		/// </summary>
		/// <param name="rect">contains the new location and size in view coordinates. </param>
		void OnPopupSize(Rect rect);

		/// <summary>
		/// Called when the IME composition range has changed.
		/// </summary>
		/// <param name="selectedRange">is the range of characters that have been selected</param>
		/// <param name="characterBounds">is the bounds of each character in view coordinates.</param>
		void OnImeCompositionRangeChanged(Range selectedRange, Rect[] characterBounds);
	}
}